The present invention relates, in general, to fingerprint pattern recognition, and more particularly, to a method for fingerprint recognition with learning capability.
A fingerprint recognition apparatus is well known which recognizes a fingerprint pattern, stores the pattern in memory, and compares the subsequent entry of a fingerprint pattern with the stored fingerprint pattern to provide a correspondence signal when they correspond with each other.
For example, a fingerprint comparison apparatus is disclosed in Japanese Patent Publication No. 76964, 1988 wherein a fingerprint image to be checked is compared with a registered fingerprint image, said apparatus including a monitor which displays the fingerprint image of the finger to be compared and an indicator displaying a finger position guide on the monitor screen. Furthermore, in Japanese Patent Publication No. 149776, 1988, a fingerprint comparison apparatus is disclosed wherein a fingerprint is scanned several times for one finger at the fingerprint scanning section during fingerprint data registration and one piece of the data captured through several sessions of scanning is registered and stored as reference fingerprint data. In this fingerprint comparison system, other scanned data are compared with the reference fingerprint data to compute the rate of correspondence, which is registered and stored, whereupon the fingerprint scanned at the fingerprint scanning section is compared with said reference fingerprint data to determine the rate of correspondence, by means of which the correspondence of the scanned fingerprints is judged on the basis of whether or not the above rate of correspondence exceeds the reference level determined according to said registered and stored rate of correspondence.
In prior art fingerprint recognition apparatus, an optical signal of a fingerprint pattern is resolved into numerous segments, each of which is quantized into a binary signal, and it is determined whether the fingerprint pattern to be compared is the same as the registered fingerprint pattern according to the degree of correspondence between the segments based on said binary signal. However, it is difficult for the subject to press his or her fingerprint against the prism at a constant pressure or in a fixed direction. Therefore, even when the fingerprint pattern of a finger is registered in memory, the rate of correspondence between the registered fingerprint pattern and the subsequently entered fingerprint pattern is low, so that fingerprint patterns must be entered many times in order to be recognized correctly.
In this respect, the fingerprint comparison system disclosed in Japanese Patent Publication No. 149776, 1988 requires multiple entries of fingerprint data at the beginning of the finger recognition process. During this process, because only one piece of fingerprint data is registered and stored, and because the rate of correspondence is compared with reference to the single piece of fingerprint data registered, the disadvantage is that the frequency of correspondence between correct fingerprint data entered and the registered fingerprint data is significantly reduced when the accuracy of fingerprint comparison is enhanced. On the other hand, when the accuracy is reduced, the frequency of correspondence may increase, but erroneous recognition of fingerprint data will also increase. Since children's fingerprint patterns change significantly over short periods of time, the fingerprint comparison system disclosed in said Japanese Patent Publication has the disadvantage of failing to accurately recognize the fingerprints of growing children.
Accordingly, it is an object of the present invention to provide a method and apparatus for recognizing a fingerprint pattern whereby a high rate of recognition is achieved by memorizing with learning capability a new fingerprint pattern having a high rate of correspondence in place of a previously stored fingerprint pattern with a low rate of correspondence.